1. Field of the Invention
The invention relates to a facsimile unit operative to read the image of a text and send the image information to another facsimile unit, and also operative to receive image information from another facsimile unit and print the image on print paper.
2. Description of the Prior Art
Conventionally, when a facsimile unit prints image information that is sent from another facsimile unit, it preliminarily compares the page length in the secondary scanning direction of the image information with the length in the secondary scanning direction (paper feed direction) of a sheet of print paper. If the page length of image information is longer than the paper length, the receiving facsimile unit prints the one-page image information divisionally on two sheets of print paper or prints it in reduced-size on a sheet of print paper.
When a facsimile unit sends image information of a text to another facsimile unit, if the width in the primary scanning direction of the text matches the width in the primary scanning direction (the dimension perpendicular to the paper feed direction) of the print paper used by the receiving facsimile unit, the sending facsimile unit reads the prescribed range of the text irrespective of the print range of the receiving facsimile unit and, after the coding process, sends the image information to the receiving facsimile unit.
Among these conventional facsimile units, a certain facsimile unit is designed, with the intention of minimizing the communication time, such that it reads a text and if a line of image information consists of only white pixels (such a line will be referred to as "white line" hereinafter), it does not send the white line to the receiving facsimile unit. Another facsimile unit is designed, with the intention of minimizing the consumption of print paper, such that it receives image information and prints the image by skipping white lines so that the printed image has a reduced size in a secondary scanning direction. Still another facsimile unit is designed, with the intention of printing a long text image effectively without size reduction nor division, such that it receives image information and if the page length of the received image information is longer than the length of print paper and image information of the excessive portion is only white pixels, it prints the image by excluding the excessive portion.
The CCITT's Recommendation T.4 on facsimile apparatus states that the line read-width of reading means is to be 215 mm.+-.1%), i.e., 1728 pixels, and the effective range of image information is to be 205 mm at a minimum. However, the text area that is guaranteed for reproduction stated in the Appendix of the CCITT's Recommendation T.4 is only 196.6 mm in a primary scanning direction, and accordingly, it connotes that part of received image information cannot actually be printed. On this account, in case the page length of received image information is longer than the length of print paper, and if line segments of blank image information exist outside of the guaranteed print range in the excessive portion, the facsimile unit cannot recognize these lines to be white lines. Consequently, the receiving facsimile unit carries out the unnecessary size reduction or division for the received image information, as shown in FIGS. 5A and 6A, printing too small, illegible characters or producing a divided useless blank page.
Another problem is that if image information is included within the read-guaranteed range but outside of the print-guaranteed range of a text page, or if a shadow of the text is created due to the flotation or skew during the text transportation, it is treated as significant image information, even though it cannot actually be printed, by the sending facsimile unit and sent to the receiving facsimile unit.